1. Field of the Invention
This invention relates to temperature control of a system or device that generates heated air, and in particular, to a temperature control that has multiple selectable temperature ranges.
2. Problems in the Art
A variety of devices utilize heated air. One example is a clothes dryer. A conventional drying mode uses internal means to heat air and supplies the heated air to the clothes in the clothes dryer for a pre-selected time period. The amount of heat provided to dry the clothes is primarily a function of the temperature of the heated air and the amount of drying time manually selected by the user. For example, if a relatively small amount of heat is needed, a shorter time period is selected. Increased amounts of heat are achieved by lengthening the time period.
However, the wide variety of available fabric types has resulted in an expansion of desired drying options for clothes dryers. For example, it can be detrimental to some fabrics to be exposed to normal dryer temperatures. It can also be detrimental to some fabrics to be exposed to normal dryer temperatures for extended periods of time, but such fabrics could sustain higher dryer temperatures during shorter periods.
Economic considerations also come into play. As is obvious, a single temperature clothes dryer requires energy to produce the heated air for drying. The single temperature must be selected to accommodate a wide variety of drying tasks. However, some drying tasks can be accomplished effectively at lower temperatures. In those cases a single temperature dryer would provide more heat than needed and consequently consume excessive amounts of energy. Most drying applications require the combination of heated air and tumbling for good results. Similarly, other applications require relatively low temperatures. In these cases, lack of flexible temperature control can result in unneeded consumption of energy. As discussed above, there are also situations where higher temperatures may be needed. Again lack of temperature flexibility may result in un-needed expenditure of energy or time during a drying application.
As a result, attempts have been made to provide for different drying temperatures in clothes dryers. See, for example, U.S. Pat. No. 4,226,026 to Deming et al and U.S. Pat. No. 3,031,768 to Kurouski. While these patents recognize that different temperatures can be advantageous for different fabrics and drying applications, their solutions are to provide multiple fixed levels of heat selectable by the user. Instead of having one dryer temperature, these patents allow selection between several fixed temperature levels.
While such a solution provides more temperature options for a user, there is still room for improvement in the art. It would be advantageous to have more flexibility in the control of heated air temperature for devices utilizing heated air. It is therefore a principal object of the present invention to provide an apparatus and method for multiple temperature range control which improves over or solves the problems and deficiencies in the art.
It is a further object of the present invention to provide an apparatus and method as above described which provides for not only multiple temperature ranges of heated air, but infinitely variable control of the temperature of the heated air within each range.
A further object of the present invention is to provide an apparatus and method as above described which provides more temperature control options for the user.
Another object of the present invention is to provide an apparatus and method as above described which is more economical with regard to energy use.
A still further object of the present invention is to provide an apparatus and method as above described which is efficient, economical, and durable.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.
The invention includes an apparatus and method for infinitely variable control of heated air temperature within multiple temperature ranges. The method includes providing a plurality of temperature ranges within normal operating temperatures of a heated air application or device. The user is allowed to select one of the plurality of temperature ranges. The user is additionally allowed infinitely variable control of temperature within the selected range.
The apparatus according to the present invention includes a temperature range mechanism which thermostatically limits the temperature of the heated air to a plurality of temperature ranges. A control mechanism allows a user to select between the temperature ranges and then infinitely variably adjust the temperature within the selected range.